Hole saw assembly

ABSTRACT

A hole-saw assembly including a hole-saw having at one end a plurality of cutting teeth and at the other end two shafts. The assembly includes a mandrel coaxially aligned with said hole-saw and including a body having two bores therethrough coaxially aligned with said shafts. An annulus located on top of the body is coaxially aligned with said mandrel and hole saw and includes two holes, the annulus rotatable around its longitudinal axis from a first to a second position. In the first position the annulus holes are aligned with the bores and shafts allowing the shafts to be freely insertable and removable and in the second position the holes are misaligned to lock the shafts to the annulus. Such an arrangement allows the hole-saw and the mandrel to be easily and quickly mountable and demountable.

BACKGROUND OF THE INVENTION

The present invention relates to an improved hole-saw assembly orarrangement and in particular to a hole-saw with a base that is easilydemountable and mountable from a mandrel engageable by a drill.

Hole-saws are a very widely used tool for many applications. Typically ahole-saw includes a flat solid base that is locked by a drill, the baseproviding support for the hole-saw. Some bases include multiple diametergrooves adapted to accommodate hole-saws of different diameters. Yetothers are single sized hole-saws.

A universal problem when using hole-saws is that when a hole has beendrilled through a material, the material that has been cut out, commonlyreferred to as the plug, remains embedded within the hole-saw and needsto be removed. Typically the plug is jammed tightly within the hole-sawand considerable force needs to be used to remove the plug using a sharpinstrument, such as a screwdriver. However, some materials, such asplastic, possess material characteristics that make their removaldifficult. The ejection of those plugs typically requires the wholehole-saw assembly to be removed from the drill to then try and force theplug out.

In response to this widely recognized problem, various improved hole-sawassemblies have been proposed that try and provide and improved methodof removing the plug. Whilst some of these have been found to work well,they are generally mechanically quite complicated. Further, the hole-sawis a dedicated size being limited to a pre-determined diameter and todrill larger size holes requires the use of a whole new hole-sawassembly.

A still further limitation of existing hole-saw assemblies is that theycan at any one time only accommodate one hole-saw and do not enable thesimultaneous use of two different sized hole-saws.

It is an object of the present invention to propose a hole-saw thatovercomes at least some of the abovementioned problems or provides thepublic with a useful alternative.

It is a further object of the present invention to provide a hole-sawassembly where the hole-saw can be easily removed from the mandrel.

It is still a further object of the present invention to provide for ahole-saw assembly wherein different sized hole-saws may be easilymounted for use with a drill.

It is yet a further object of the present invention to provide for ahole-saw assembly wherein at least two different sized hole-saws may beused simultaneously in drilling a larger hole.

SUMMARY OF THE INVENTION

Therefore in one form of the invention there is proposed a hole-sawassembly including:

-   a hole-saw having at one end a plurality of cutting teeth and at the    other end two shafts;-   a mandrel coaxially aligned with said hole-saw and including a body    having two bores therethrough coaxially aligned with said shafts;-   an annulus coaxially aligned with said mandrel and hole saw and    including two holes, said annulus rotatable around its longitudinal    axis from a first to a second position, wherein in said first    position said annulus holes are aligned with said bores and said    shafts allowing said shafts to be freely insertable and removable    and in said second position said holes being misaligned thereby    locking said shafts to said annulus.

Preferably said annulus is biased to said second position.

Preferably said assembly includes a base from which therein extend thetwo shafts said base including a mounting means for mounting of ahole-saw thereon.

Preferably said hole-saw includes a threaded inner bore adapted toengage a threader outer projection extending from said base.

In a preferred embodiment said shafts include a flute adjacent saidouter end and a cap on said outer end, the cap having an inner surfaceadapted to engage the annulus when said annulus is in said secondposition to thereby lock the shafts from longitudinal movement from theannulus.

Preferably said assembly includes a drill-bit mounted on said mandrel,said drill-bit extending through and beyond said hole-saw.

In a further from of the invention there is proposed a hole-saw assemblyincluding:

-   a hole-saw having a longitudinal body with a plurality of cutting    teeth at one end and a threaded inner bore at the other end;-   a base including a disk co-axially aligned with said hole-saw body    and including a threaded projection extending longitudinally    therefrom, said projection adapted to be engaged by said hole-saw    threaded bore, said disk including a pair of shafts extending in a    longitudinal direction away from said hole-saw, each said shaft    including a column adjacent said base a flute adjacent said shaft    outer end and a chamfered cap, the diameter of said cap equal to the    diameter of said column;-   a mandrel co-axially aligned with said base and hole-saw and    including a body having a drill bit extending therefrom, said drill    bit passing through central apertures in the base and said hole-saw,    said mandrel further having two bores therethrough co-axially    aligned with said base shafts;-   a annulus resting on top of said base and being rotatable between a    first and a second position, said annulus further including two    holes wherein said holes in the first position are aligned with the    bores in said mandrel and the shafts of said base, and in said    second position are misaligned, the thickness of the mandrel body    and annulus being such that the flute is engaged by said annulus    with the cap extending beyond the annulus so that when in said    second position the annulus locks said shafts in a relative    longitudinal position.

In a preferred embodiment said assembly includes an inner and an outerhole-saw mounted on said mandrel, said inner hole-saw extending beyondsaid outer hole-saw.

In a still further form of the invention there is proposed a hole-sawarrangement for use in a drilling machine including a hole-saw and amandrel assembly characterised in that there is included a biased memberwhich when in a first position, is adapted to engage with and lockinglyretain said hole-saw when it is mounted onto said mandrel and uponmovement to a second position, said biased member is adapted to unlockand release said hole-saw allowing said mandrel and said hole-saw to beseparated.

In preference the mandrel assembly includes a body that rotationallysupports the biased member at one end and a hole-saw boss at the other.

In preference the hole-saw boss includes at one end a thread forengaging with a thread in the hole-saw with the opposite end having atleast two extending pins which are inserted into at least two holes inthe body so that the hole-saw boss and body are rotationally engaged.

In preference the biased member is a spring-loaded rotatable ring thatinteracts with a taper on the extending pins on insertion into the mainbody to move away from a first position to a second position. In thissecond position the rotatable ring engages shoulders on the extendablepin to lock the hole-saw boss and main body together.

In preference upon rotation of the rotatable ring back toward the firstposition, the shoulders are disengaged and the hole saw boss is unlockedand can be slidably removed.

In preference the range of movement of the rotatable ring is limited byinteraction of an abutment and a pin contained in the rotatable ring andthe main body.

An advantage of such an arrangement is that a hole saw may be rapidlyremoved and re-attached to a mandrel without the use of threads andwithout the use of a tool. This is particularly advantageous when thehole saw becomes clogged and needs to be cleared or when the hole saw isinterchanged with a hole saw of a different size.

Still a further advantage is that by utilising a boss, commonlyavailable hole-saws may be used with the mandrel.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several implementations of theinvention and, together with the description, serve to explain theadvantages and principles of the invention. In the drawings:

FIG. 1 is an exploded isometric view of a hole-saw assembly embodyingthe present invention;

FIG. 2 is a side view of the hole-saw assembly base mandrel embodyingthe present invention;

FIG. 3 is a top view of the mandrel of FIG. 2;

FIG. 4 is a side view of the hole-saw assembly as the hole-saw and baseis mounted on the mandrel;

FIG. 5 is a partial cross-sectional view illustrating the engagement ofthe hole-saw base with the mandrel;

FIG. 6 is a detailed partial underside perspective view of the lockingmechanism of the mandrel when in a locked or biased position;

FIG. 7 is the mechanism of FIG. 6 when in an unlocked position;

FIG. 8 is a perspective view of an alternate hole-saw and base embodyingthe present invention when formed in one piece;

FIG. 9 is a perspective view of a large diameter hole-saw and baseembodying the present invention;

FIG. 10 is a perspective view of a hole-saw assembly embodying thepresent invention and having two hole-saws, one within the other forguiding the larger hole-saw;

FIG. 11 is a perspective view of a hole-saw assembly according to yet afurther embodiment of the invention and where the shafts of the hole-sawbase are housed within the mandrel and do not protrude through its uppersurface;

FIG. 12 is a perspective view of the hole-saw and base of FIG. 11illustrating the shorter shafts; and

FIG. 13 is a cross-sectional view of the hole-saw assembly of FIG. 11when the hole-saw and base are mounted to the mandrel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description of the invention refers to theaccompanying drawings. Although the description includes exemplaryembodiments, other embodiments are possible, and changes may be made tothe embodiments described without departing from the spirit and scope ofthe invention. Wherever possible, the same reference numbers will beused throughout the drawings and the following description to refer tothe same and like parts.

Referring to FIGS. 1 to 5 there is shown a hole-saw assembly 10including a hole-saw 12, base 14, and mandrel 16.

The hole-saw 12 includes a cylindrical body 18 having cutting teeth 20at one end thereof. At the opposite end the hole-saw 12 includes athreaded bore 22 (with inner threads), the outer surface of the hole-sawbody 18 adjacent the bore 22 including circumferentially disposedshoulders 24 to enable a tool (not shown) such as a wrench to engage thehole-saw 12 for rotational movement thereof.

The base 14 includes disk 26. Extending co-axially from the disk 26 is athreaded projection 28 (with outer threads), of a size and shape to beengaged by the bore 22 thus enabling hole-saw 12 to be tightly screwedonto the base. The disk 26 includes shoulders 30 for engagement by atool. Those skilled in the art will appreciate that the use of twotools, one on the hole-saw 12 and one on the base 14, the hole-saw mayalso be removed from the base.

Extending adjacent the edge of the disk 26 and in the opposite directionto the projection 28 are two identical shafts 32 and 34. Since theshafts perform the same function and operate in exactly the same way,only one will be described in the rest of the description. It is howeverto be understood that the description applies equally well to both.

Shaft 32 includes a column 36 extending from the disk and attached tothe disk using well-known techniques such as threads or press fitting.Adjacent the outer end of the column 36 is a flute 40, the column thenhaving a chamfered cap 42 fixed on its outer end whose outer diameter isequal to the diameter of the column 36.

The mandrel 16 includes a longitudinal body 44 extending co-axially fromand rotationally affixed to which is a drill bit 46. Extending in theopposite direction to the drill bit 46 is an arbour 48 having shoulders50 and is insertable into a drill (not shown) as is well known in theart. The body 44 includes two holes 52 and 54 whose location and size issuch to allow for the insertion and passage through of shafts 32 and 34therein, shaft 32 insertable into hole 52 and shaft 34 insertable intohole 54. Typically, the holes 52 and 54 are of a diameter to effectivelyenable the shaft to be mounted to the body 44.

The length of the body 44 is the same length as that of the shaft column36 from the disk 26 to the flute 40 so that when the shaft 32 isinserted into body 44 the flute and the cap protrude beyond the body 44.

Located on top of the body 44 is a co-axial annulus or ring 56,rotatably movable between a first and a second position. The annulus 56includes two correspondingly shaped and sized apertures 58 and 60 thatare aligned with the holes 52 and 54 when the annulus is in the firstposition and are misaligned when the annulus is in the second position.

Those skilled in the art will appreciate that the shaft flute 40 and cap42 then extend into the annulus when it is aligned with the body. Thethickness of the annulus 56 is equal to the width of the flute 40 sothat when fully inserted into the mandrel only the cap 42 extends beyondthe surface plane of the annulus 56.

When the annulus is in the second position with the shaft 32 fullyinserted into the mandrel, the upper surface of the annulus 62 engagesthe lip 64 of the cap 42, effectively preventing the shaft 32 from beingwithdrawn from the mandrel 16. This effectively therefore locks the base14 and hence the hole-saw 12 to the mandrel 16 enabling the hole-saw tobe used to drill a hole.

The annulus is biased to the second position, that is, the lockedposition and a rotational force has to be applied to rotate it to thefirst position to enable for the withdrawal of the shafts 32 and 34. Therotation from the biased second position to the first position isgenerally in the same direction as the rotation of the drill.

The skilled addressee will now appreciate that the present hole-sawassembly enables for the very quick mounting and unmounting of ahole-saw and base to a mandrel that is already mounted in a drill. Sincethe diameter of the hole-saw is independent of the size of the base andhence the mandrel, one may have a number of hole-saws that they simplymount and unmount to and from the mandrel by rotating the annulusbetween the first and second positions.

However, to further assist in quick mounting of the hole-saw base 14 tothe mandrel 16, the circular edges 66 of holes 58 and 60 on theunderside 68 of the annulus 56, that is the side that faces the base 44,may be tapered or chamfered. As the shafts 32 and 34 are inserted intothe mandrel through holes 52 and 54 and apertures 58 and 60, the capforces the annulus to rotate to the first position. As the cap passesbeyond the upper surface of the annulus, the biasing means causes it tosnap back into its biased position thereby locking the base and hencethe hole-saw to the mandrel. This provides the tool operator with anautomatic “snap-fit” arrangement.

Body 44 is typically clamped onto the drill bit 46 using a grub screw70. However, it may equally well be attached, as would be known by theskilled addressee, using other common techniques.

The annulus is secured in its position using a circlip 72. To preventrotation of the circlip that may effectively block one of the apertures58 or 60, a cusp (not shown) or projection may be used to lock thecirclip relative to the annulus.

Referring now to FIGS. 6 and 7 there is shown in detail the annulus 56and specifically the biasing arrangement. The annulus includes a groove74 within which is located the biasing means, typically a spring 73. Atone end of the groove is located a channel 76 within which slidablymoves a pin 78. The pin engages a correspondingly shaped bore (notshown) in the body 44 whereby it is locked into place when the annulusis placed on top of the body. The length of the channel 76 within whichthe pin can effectively move, the two positions illustrated in FIGS. 6and 7, then limits rotation of the annulus as shown in FIG. 3.

In a preferred embodiment, the hole-saw may be manufactured integrallywith the shafts that engage the mandrel. This embodiment is illustratedin FIG. 8 wherein one can see that the hole-saw 80 has integral shafts82 and 84 whose shape and function is the same as discussed earlier.Such a hole-saw may be for example be manufactured using machining ormetal casting processes. An advantage of this is in the reduction ofparts for manufacture resulting in reduced costs.

To assist in handling the shafts they may include shoulders 86 that canbe engaged by a tool, the shoulder also a feature of the earlierembodiment.

In the case where the hole-saw is of a significant diameter, asillustrated in FIG. 9, the hole-saw 88 may be attached to the base 90not by using threaded engagement members but rather by the use of screws92 and 94 that pass through apertures 96 and 98 in the bottom of thehole-saw and engage the ends of shafts 100 and 102 respectively therebylocking the hole-saw to the base 90.

In an alternate embodiment, the projection 28 of the base 14 illustratedin FIGS. 1–5 may be made significantly longer than is currently known.This would then enable two hole-saws to be mounted on the one base. Thisis a particularly useful feature where the operator may wish to drill abigger hole over an existing hole wherein the size of the smallerhole-saw is chosen to be the size of the already existing hole. Thesmaller hole-saw is then used as an effective guide center to be able tocut out the bigger hole in a symmetrical arrangement. As illustrated inFIG. 10 the hole-saw assembly according to this preferred embodimentincludes a smaller hole-saw 104 that extends beyond a larger hole-saw106 in the longitudinal direction. The diameter of the smaller hole-saw104 is chosen so that its outside surface 108 engages the inner surfaceof hole 110 in wall 112. The smaller hole-saw 104 ensures that whenhole-saw 106 engages the wall, it does not gyrate ensuring that thelarger hole 114 to be cut-out in the wall is co-axial with the smallerhole 110.

Illustrated in FIGS. 11 to 13 is a hole-saw assembly according to afurther preferred embodiment of the present invention. In thisembodiment the hole-saw 12 and base 26 are of the same type as describedabove. However the total length of the shafts 116 and 118 are somewhatshorter, the shafts still having flutes 40 and caps 42. The shortershafts, assuming that the base and the annulus are the same size,results in the shafts not protruding beyond the annulus as was the casein the earlier embodiment. This is clearly illustrated in FIGS. 11 and13 where one can see that the shafts 116 and 118 do not protrude beyondthe upper surface 120 of the annulus 122.

Since the shafts 116 and 118 no longer protrude beyond the annulus 56,the previously described locking technique of the mandrel to the shaftsis no longer available. For that reason, holes 124 and 126 adjacent theupper surface 120 of the annulus 56 are partially enlarged to provide aninner shoulder 128 that can be engaged by the lip 64 of the cap 42.Accordingly, the annulus holes 124 and 126 are of a circularcross-section only for the length of the flute 40 from the annulusbottom surface 68, and are then enlarged to accommodate for therotational movement of the annulus 56 to lock and unlock the shafts 116and 118 to the mandrel.

This embodiment overcomes the need for a dimple or the like to preventthe clip 72 from any rotational movement. It also provides for a morevisually pleasing appearance and reduces the risk of the caps catching.

Further advantages and improvements may very well be made to the presentinvention without deviating from its scope. Although the invention hasbeen shown and described in what is conceived to be the most practicaland preferred embodiment, it is recognized that departures may be madetherefrom within the scope and spirit of the invention, which is not tobe limited to the details disclosed herein but is to be accorded thefull scope of the claims so as to embrace any and all equivalent devicesand apparatus.

In any claims that follow and in the summary of the invention, exceptwhere the context requires otherwise due to express language ornecessary implication, the word “comprising” is used in the sense of“including”, i.e. the features specified may be associated with furtherfeatures in various embodiments of the invention.

1. A rotational tool support assembly including: a boss adapted at oneend to support a tool and at the other end two shafts; a driving meanscoaxially aligned with said boss and including a body having two borestherethrough coaxially aligned with said shafts; a locking ringcoaxially aligned with said driving means and boss and including twoholes, said locking ring rotatable around its longitudinal axis from afirst to a second position, wherein in said first position said lockingring holes are aligned with said bores and said shafts allowing saidshafts to be freely insertable and removable and in said second positionsaid holes being misaligned thereby locking said shafts to said lockingring.
 2. A hole-saw assembly including: a hole-saw having at one end aplurality of cutting teeth and at the other end two shafts; a mandrelcoaxially aligned with said hole-saw and including a body having twobores therethrough coaxially aligned with said shafts; a locking memberforming part of said mandrel and including two holes, said lockingmember moveable from a first to a second position, wherein in said firstposition said locking member holes are aligned with said bores and saidshafts allowing said shafts to be freely insertable and removable and insaid second position said holes being misaligned thereby locking saidshafts to said locking member.
 3. A hole-saw assembly as in claim 2wherein said locking member is biased to said second position.
 4. Ahole-saw assembly as in claim 2 wherein said assembly includes a basefrom which therein extend the two shafts, said base including a mountingmeans for mounting of a hole-saw thereon.
 5. A hole-saw assembly as inclaim 4 wherein said hole-saw includes a threaded inner bore adapted toengage a threaded outer projection extending from said base.
 6. Ahole-saw assembly as in claim 2 wherein said shafts include a fluteadjacent said outer end and a cap on said outer end, the cap having aninner surface adapted to engage the locking member when said lockingmember is in said second position to thereby lock the shafts fromlongitudinal movement from the locking member.
 7. A hole-saw assembly asin claim 2 including a drill-bit mounted on said mandrel, said drill-bitextending through and beyond said hole-saw.
 8. A hole-saw assembly as inclaim 2 where said locking member is an annulus coaxially aligned withsaid mandrel.
 9. A hole-saw assembly as in claim 8 wherein said annulusis rotatable around its longitudinal axis from said first to said secondposition.
 10. A hole-saw assembly including: a hole-saw having alongitudinal body with a plurality of cutting teeth at one end and athreaded inner bore at the other end; a base including a disk co-axiallyaligned with said hole-saw body and including a threaded projectionextending longitudinally therefrom, said projection adapted to beengaged by said hole-saw threaded bore, said disk including a pair ofshafts extending in a longitudinal direction away from said hole-saw,each said shaft including a column adjacent said base, a flute adjacentsaid shaft outer end and a chamfered cap, the diameter of said cap equalto the diameter of said column; a mandrel co-axially aligned with saidbase and hole-saw and including a body having a drill bit extendingtherefrom, said drill bit passing through central apertures in the baseand said hole-saw, said mandrel further having two bores therethroughco-axially aligned with said base shafts; an annulus resting on top ofsaid base and being rotatable between a first and second position, saidannulus further including two holes wherein said holes in the firstposition are aligned with the bores in said mandrel and the shafts ofsaid base, and in said second position are misaligned, the thickness ofthe mandrel body and annulus being such that the flute is engaged bysaid annulus with the cap extending beyond the annulus so that when insaid second position the annulus locks said shafts in a relativelongitudinal position.
 11. A hole-saw assembly as in claim 10, saidassembly including an inner and an outer hole-saw mounted on saidmandrel, said inner hole-saw extending beyond said outer hole-saw.
 12. Arotational tool support assembly including: a boss adapted at one end tosupport a tool and at the other end at least one shaft; a driving meanscoaxially aligned with said boss and including a body having at leastone bore therethrough coaxially aligned with said at least one shaft; alocking ring coaxially aligned with said driving means and boss andincluding at least one hole, said locking ring rotatable around itslongitudinal axis from a first to a second position, wherein in saidfirst position said at least one hole of said locking ring is alignedwith said at least one bore and said at least one shaft, therebyallowing said at least one shaft to be freely insertable and removable;and in said second position said at least one hole being misaligned,thereby locking said at least one shaft to said locking ring.
 13. Ahole-saw assembly including: a hole-saw having at one end a plurality ofcutting teeth and at the other end at least one shaft; a mandrelcoaxially aligned with said hole-saw and including a body having atleast one bore therethrough coaxially aligned with said at least oneshaft; a locking member forming part of said mandrel and including atleast one hole, said locking member moveable from a first to a secondposition, wherein in said first position said at least one hole of saidlocking member is aligned with said at least one bore and said at leastone shaft, allowing said at least one shaft to be freely insertable andremovable; and in said second position said at least one hole beingmisaligned thereby locking said at least one shaft to said lockingmember.
 14. A hole-saw assembly as in claim 13 wherein said lockingmember is biased to said second position.
 15. A hole-saw assembly as inclaim 13 wherein said assembly includes a base from which therein extendthe at least one shaft, said base including a mounting means formounting of a hole-saw thereon.
 16. A hole-saw assembly as in claim 15wherein said hole-saw includes a threaded inner bore adapted to engage athreaded outer projection extending from said base.
 17. A hole-sawassembly as in claim 13, wherein said at least one shaft includes aflute adjacent said outer end and a cap on said outer end, the caphaving an inner surface adapted to engage the locking member when saidlocking member is in said second position to thereby lock the at leastone shaft from longitudinal movement from the locking member.
 18. Ahole-saw assembly as in claim 13, including a drill-bit mounted on saidmandrel, said drill-bit extending through and beyond said hole-saw. 19.A hole-saw assembly including: a hole-saw having a longitudinal bodywith a plurality of cutting teeth at one end and a threaded inner boreat the other end; a base including a disk co-axially aligned with saidhole-saw body and including a threaded projection extendinglongitudinally therefrom, said projection adapted to be engaged by saidhole-saw threaded bore, said disk including at least one shaft extendingin a longitudinal direction away from said hole-saw, said at least oneshaft including a column adjacent said base, a flute adjacent said shaftouter end and a chamfered cap, the diameter of said cap equal to thediameter of said column; a mandrel co-axially aligned with said base andhole-saw and including a body having a drill bit extending therefrom,said drill bit passing through a central aperture in the base and saidhole-saw, said mandrel further having at least one bore therethroughco-axially aligned with said at least one shaft of said base; an annulusresting on top of said base and being rotatable between a first andsecond position, said annulus further including at least one hole,wherein said at least one hole in the first position is aligned with theat least one bore in said mandrel and the at least one shaft of saidbase, and in said second position is misaligned, the thickness of themandrel body and annulus being such that the flute is engaged by saidannulus with the cap extending beyond the annulus so that when in saidsecond position the annulus locks said at least one shaft in a relativelongitudinal position.
 20. A hole-saw assembly as in claim 19, saidassembly including an inner and an outer hole-saw mounted on saidmandrel, said inner hole-saw extending beyond said outer hole-saw.